Not sure where you have found a report stating that only one sub is currently crewed.
Latest update I have at hand states:
"As of early 2011 the navy was still one submarine crew short of the Australian Defence Force's manpower target for the submersible fleet. While the situation had improved markedly since the period from June to October 2009, when only one submarine could put to sea, the navy only had crews for three of the six Collins Class boats.
Navy's submarine target is four submarines crewed and in various stages of their routine operating, maintenance and training cycles," a Defence spokesman said. "This allows navy to meet its training and operational preparedness requirements."
As for history of problems with the subs, they have all been rectified, the Collins is now considered one of the most advanced and efficient conventional submarines in the world.
The biggest upgrade came when they updated the combat systems. They are now equipped with the tactical command and control system 'AN/BYG-1', back-fitted from the US Navy's Los Angeles, Seawolf, and SSGN-class submarines.
As for Russian and Chinese Subs, Australia should never purchase military hardware from possible future adversary for obvious reasons.
As for the SU-35 that is a fourth generation fighter equivalent to the F-18 Super Hornet, the F-35 is fifth generation fighter/strike, far superior and more advanced than the SU-35. It is the best fighter/strike aircraft for Australia and will likely serve Australia extremely well for generations to come.
SU-35 might be good for airshows with it's thrust vectoring tricks but thats about it. Also the SU-35 is a large fighter, it's radar cross section is huge compared to a F-35, F22.
